Tell it which color is the background color, color numbers are in the top-right, and an image using those numbers is at the bottom. (Tip: click CHANGE COLORS if screen color conflicts with any sprite color)

and get the results

The way the vector image is created is to check the neighbors (up/down/left/right, ignoring diagonals) of each pixel. If all 4 neighbors are on, then turn the pixel off.

Next I need to make a converter that merges the vector routines with the 2x sprite routines from my Two Color converter (which I used for the dragon graphics in Medieval Mayhem).